In order for your body to survive and thrive, you need food. Once food is in your system, your metabolism takes over, converting food into energy you need for daily life. The amount of energy a certain food or drink contains is measured in calories.

Consuming too little calories can lead to nutritional deficiencies, while too many calories can lead to obesity.

So, how exactly do you decide how many calories you need?

How Many Calories Do You Need?

According to dietary guidelines from the U.S. Department of Agriculture, adults over age 21 should aim to consume between 1,600 and 3,000 daily calories.

However, there are many factors that determine individual caloric needs, including:

Although you can’t change your age, height, genetics or other biological factors that influence your caloric needs, the one thing you do have control over is your level of physical activity.

The amount of exercise you do on a regular basis has a direct impact on how many calories you need in a day. If you are looking to lose weight, make sure that you do not eat the calories you burned. If you are looking to maintain your weight, you’ll need to add approximately that amount of calories into your caloric intake.

The type of exercise you do and how much muscle mass you carry also factor into how many calories you need. Strength training, in particular, builds lean muscle, and the more lean muscle your body is made out of, the more calories your body needs to fuel itself. Therefore, two people with the same body weight but have different proportions of lean muscle mass to fat will have different daily caloric needs. The person with more lean muscle mass will need more calories to maintain their weight.

Calculating daily calories to maintain weight

A calorie is a measure of the energy in food. Everyone requires a certain amount of calories in order for your body to maintain basic, life-sustaining functions, such as breathing, circulating blood and digesting. This minimum number, which is unique to everyone, is the basal metabolic rate.

Calorie Calculator: How Many Calories Do You Need?

By inputting your gender, current weight, height, age and activity level, this calculator will help you estimate your BMR to determine how many calories you need.

What’s a Calorie Deficit?

When determining your calorie needs, keep in mind the difference between a calorie deficit and a calorie surplus.

Calorie deficit

A calorie or caloric deficit occurs when calorie intake is less than calorie expenditure. People use calorie deficits and follow low-calorie diets to lose weight and maintain weight loss.

“Traditionally, a calorie reduction of 350 to 500 calories per day has been considered a safe starting point for an average adult,” says Vanessa King, a registered dietitian and spokesperson for the Academy of Nutrition and Dietetics. “Too high a calorie deficit leads to extra muscle loss. A weight loss goal of 0.7 to 1.5 pounds per week is considered realistic and achievable.”

She adds that personalized targets based on an individual’s goals, their attitudes about calorie restriction and their lifestyle will have better outcomes.

If you are trying to lose some weight and are cutting calories from your target daily intake, be sure not to do it to an unsafe degree.

“You need to be concerned about nutrient deficiencies with undereating, which can lead to heart problems and muscle loss,” King warns. “Too little calories means too little energy for physical activity and pleasurable activities. Over time, extreme calorie deficit can lead to malnutrition and organ failure.”

Calorie surplus

Conversely, a calorie surplus is when you consume more calories than you burn, resulting in an increase in body mass.

If you are looking to increase your weight or muscle mass, this is when you will need to eat a higher amount of calories than your body burns to meet your caloric surplus goals. For most people who want to gain muscle, experts suggest consuming 10% to 20% additional calories.

Benefits of Counting Calories

Whether you’re trying to lose weight or gain weight, counting calories can help you reach your health and fitness goals.

By being more aware of what you eat each day and tracking your caloric intake, you’ll be able to adjust your diet and habits accordingly.

But not all calories are created equal. Calories are a measure of energy in food, but it’s about nutritional quality over quantity when it comes to healthy eating. That means what types of foods you consume are more important than how many calories you take in.

For example, a 4-ounce fruit snack pack may contain 90 calories and vitamins A, C and E, but it’s largely made up of corn syrup, preservatives and other highly processed ingredients.

“The fruit snack is great if you want a quick burst of energy in a small package,” King says.

However, if you were to consume the same amount of calories in the form of fresh blueberries, you would get 1 cup and reap all the health-promoting, disease-fighting benefits from the nutrient-dense fruit, including antioxidants, phytonutrients, vitamins, minerals, fiber and natural sugars.

When deciding on what foods to eat, keep to your caloric target number and remember to pick unprocessed foods, such as:

Unprocessed foods will allow you to nutritionally get more “bang for your buck” and help you feel fuller for longer. Limit your intake of ultra-processed foods, like chips, french fries, pastries and soda.

“Americans who eat more ultra-processed foods versus unprocessed foods can accidentally eat 500 more calories a day, both because they feel less satisfied and because they ate faster,” says Bethany Doerfler, a registered dietitian and gastroenterology research specialist at the digestive health center at Northwestern Medicine in Chicago.

Risks of Counting Daily Calories

While it’s easy to get fixated on counting calories, it often doesn’t produce consistent outcomes. That’s because calorie calculations are not an exact science. Many times, people underestimate how many calories they are eating unless they are carefully measuring, weighing and observing every item they put food in their mouths.

In addition, no two people are the same. The way that calories are consumed by the body varies, so you can eat the same amount of calories as your next door neighbor but have very different results with your weight.

Focusing on meticulously counting each calorie can increase the risk of disordered eating – such as orthorexia, a condition characterized by an unhealthy obsession with healthy eating – and can cause some people to lose sight of the most important ingredient to overall health: the quality of food.

“Put the focus more on food quality and achieving healthy lifestyle practices to attain a healthy weight,” King says.

Tips for Keeping to Your Calorie Target

The push and pull of daily life can put being mindful about your caloric intake on the back burner. Here are some tips to help you keep to your target goals: